My kalkwasser container is a 15 gal barrel that would be sealed if I screwed the cap down all the way. I leave the cap just a little loose…. How big is your vent? Pinhole should be enough, but not too much.
Welcome Andrew! I’m also in San Jose.
You should be near the end of the uglies. I transferred from my bio cube to RS 170 and it was about a year for stability, if I recall correctly